Bump postcss-loader from 7.3.4 to 8.0.0

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 7.3.4 to 8.0.0.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/postcss-loader/compare/v7.3.4...v8.0.0)

---
updated-dependencies:
- dependency-name: postcss-loader
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -55,7 +55,7 @@
     "lato-font": "^3.0.0",
     "mini-css-extract-plugin": "^2.7.7",
     "postcss": "^8.4.33",
-    "postcss-loader": "^7.3.3",
+    "postcss-loader": "^8.0.0",
     "postcss-scss": "^4.0.9",
     "sass": "^1.70.0",
     "sass-loader": "^13.3.2",